Friction element and method of making the same



Patented June 30, 1931 PATENT OFFIC JAMES DRISCOLI, OF PLAINFIELD, NEW JERSEY, ASSIGNOR TO J'OHNS-MANVILLE COR- PORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK FRICTION ELEMENT AND METHOD OI MAKING THE SAME ll'o Drawing.

The present invention relates to an imgrovement in friction elements having a brous asbestos body or base, and in its specific aspect is concerned particularly with I an improved friction element having a body portion of woven asbestos yarn.

The invention has as its primar ob'ect the provision of a friction element w ich as a. much less tendency to score than the friction elements now available, and the accomplishment of this object without the loss of other desirable qualities such as high tensile strength.

A further object is the provision of a lining of increased density and firmness.

hese and other desirable objects are attained according to my invention by incorporating finely divided or powdered zinc with the fibrous asbestos which forms the body or base of the friction element. Al-

though the invention is not restricted to any particular theory of action it is probable that the resulting elimination or very sub stantial reduction in the tendency of the friction element to score is due to a gradual deposition of zinc from the friction element on to the metallic surface of the drum in the form of an adherent film or coating. The film of zinc thus formed serves to largely prevent the abrasion of metal from the drum and subsequent bedding and coalescense of the same in the friction element, thereby obviating the principal cause of scoring.

While my invention contemplates the improvement of fibrous asbestos friction elements of both the woven and felted types, it is particularly concerned with the provision of an element adapted for use as a brake lining and formed from woven asbestos yarn having powdered zinc incorporated therewith. The zinc powder is preferably incorporated with the yarn by applying a mixture or paste containing the requisite amount of zinc powder to the surface of the yarn prior to the weaving operation. The latter operation may be advantageously efi'ected while the coated yarn is still moist. The coated yarn is then woven into the requisite shape as for instance into a tape or Application filed February 21, 1930. Serial No. 430,447.

having the following composition by weight:

Percent Bentonite clay 4.28 \Vater 47.70 Zinc owder 47.70 Stare 0.32

The bentonite serves as a suspending agent for the zinc but various other known suspending agents may be substituted therefore if desired. The starch serves as an adhesive material and assists in forming an adherent coating of the zinc powder which will not brush off during the subsequent operations.

The proportions and ingredients given in this example may be widely varied, the principal requirement being that the mixture contain in suspension, a suitable amount of the zinc powder to form a practically continuous coating on the yarn.

The zinc powder may be incorporated with the yarn in various other ways as for instance by first moistening the yarn with a suitable liquid and then drawing the wet yarn thru a bank of the powdered zinc. The zinc powder may also be incorporated in the finish for asbestos paper and thin strips of the paper thusprovided spun into yarn with a wire reinforcement in the usual manner. The zinc powder may also be admixed with the loose absestos fibers prior to the spinning of the same into yarn. Various other methods of incorporating the Zinc powder will occur to those versed in the art. However none of these methods have the specific advantages of the method particularly described herein.

The zinc powder employed is the commercial article sometimes termed zinc dust and is fairly finely sub-divided, for instance, of sufiicient fineness to pass thru a 100 mesh to the inch screen.

The asbestos yarn is preferably reenforced with a strand of a suitable metal as for example with brass wire. All the yarn entering into the finished fabric may be coated with zinc or only a part thereof depending upon the particular results desired. Excellent results have been obtained by coating only the warps and binders and leaving the fill yarn uncoated.

The zinc coating may be advantageously applied to the yarn by causing it to pass thru a bank of the sludge while the yarn is being wound on to beams or bobbins preparatory to the weaving operation.

The coated yarn is preferably woven while still moist as any tendency for the coating to brush or peel off is materially re duced thereby. The coated yarn if desired may be braided into the desired shapes, and the term weaving as used in the claims includes braiding as well as the conventional weaving operation.

The woven listing is caleudered and then completely dried. preferably by heat in an oven. A typical example of the composition of the listing prior to impregnation is as follows:

Percent Brass wire 19. 25 Zinc dust 18. 44

Bentonite 1.65 Asbestos yarn 60. 66

The dried lining may then be impregnated with any suitable saturant. A suitable saturant for instance, is a liquid of the following composition by weight Per cent Pitch 14.00 Blown China wool oil 21.00 Varnoline 65.00

The saturated lining is then dried and baked or cured in a dry heat oven.

In the production of friction elements having a felted fibrous asbestos base commonly termed mill-board, the requisite amount of zinc owder' may be introduced prior to the felting operation by adding it directly to the asbestos pulp.

Friction elements produced accordin to the above described methods have een found by severe service tests to have a very marked decreased tendency to score brake drums and this advantage is obtained without loss of other desirable qualities. I have found that the introduction of zinc into the friction element in the form of zinc wire re enforcement for the yarn is not satisfactory since the strength of the zinc wire is greatly reduced when subjected to the elevated temperatures incident to the processing and use of the friction element. By the combination of zinc powder with asbestos yarn having a wire insertion as for instance rass wire according to my invention, a. brake lining is provided having a tensile strength and other desirable qualities equal to the conventional type of brake lining and characterized by a greatly decreased tendency to score brake drums. The improved lining is further characterized by its in= creased density and comparative firmness which materially reduces the frequency of necessary brake adjustments.

What I claim is l. A method of manufacturing fibrous asbestos friction elements which comprises incorporating powdered zinc with the asbestos in sufficient quantity to substantially reduce the tendency of the element to score during use.

2. A method of manufacturing friction elements which comprises incorporating powdered zinc with asbestos yarn and then weaving the yarn into the requisite shape.

3. A method of manufacturing friction elements which comprises applying a coating of powdered zinc to asbestos yarn and then weaving the yarn into the requisite shape.

4. A method of manufacturing friction elements which comprises coating asbestos yarn with a mixture containing powdered zinc in suspension and then weaving the yarn into the requisite shape.

5. A method of manufacturing friction elements which comprises drawing asbestos yarn thru a mixture containing powdered zinc in suspension and then weaving the yarn while still moist into the requisite s ape.

6. A method of manufacturing friction elements which comprises applying a coating to asbestos yarn of an aqueous suspension of zinc and weaving the yarn into the requisite shape.

7. A method of manufacturing friction elements which comprises applying a coating to asbestos yarn of an aqueous mixture containing zinc, a suspending agent therefor and an adhesive material, and then weaving the yarn into the requisite shape.

8. A method of manufacturing friction elements which comprises applying to asbestos yarn a coating of a mixture of a colloidal clay, zinc powder and and an adhesive material, and weaving the yarn into the requisite shape.

9. A method of manufacturing friction bestos yarn a coating of a mixture of a colloidal clay and zinc powder and weaving the yarn into the requisite shape.

10. A griction element comprising a fibrous asbestos base having owdered zinc incorporated therewith in su cient quantity to su stantially reduce the tendency of the element to score during use.

11. A friction element 'comprising a base of woven asbestos yarn having powdered zinc incorporated therewith.

12. A friction element comprising a base of woven asbestos yarn coated with powdered zinc.

13. A friction element comprising a base of woven reenforced asbestos yarn coated with powdered zinc.

14. A brake lining comprising a base of -woven asbestos yarn reenforced with a strand of metal, the surface of said am being provided with a coating of pow ered zinc.

15. A brake lining comprising a base of woven asbestos yarn reenforced with brass wire, the surface of said yarn being provided with a coating of powdered zinc.

Signed at Manville in the county of Somerset and Stateof New Jersey, this 17th day of February, A. D. 1930.

JAMES DRISCOLL.

loidal clay and zinc powder and weaving the yarn into the IEtilllSitG shape.

10. A i riction e ement comprising a fibrous asbestos base having owdered zinc incorporated therewith in so cient quantity m zinc incorporated therewith.

12. A friction element comprising a base of woven asbestos yarn coated with powdered zinc.

13. A friction element comprising a base of woven reenforced asbestos yarn coated with powdered zinc.

14. A brake lining comprising a base of woven asbestos yarn reenforced with a strand of metal, the surface of said am being provided with a coating of pow ered zinc.

15. A brake lining com rising a base of woven asbestos yarn reen orced with brass wire, the surface of said yarn being provided with a coating of powdered zinc.

Signed at Manville in the county of Somerset and Stateof New Jersey, this 17th day of February, A. D. 1930.

JAMES DRISCOLL.

CERTIFICATE OF CORRECTION. Patent No. 1,812,326. A I Granted June 30, 1931, to JAMES DRlSCOLL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows; Page 1, line 56, for "and" read an; line 90, for "finish" read furnish; page 2, line 46, for "wool" read wood; and that the said LettersPatent should be read with these'corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 29th day of September, A. D. 1931.

M. J. Moore, (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 1,812,326. Granted June 30, 1931. to

JAMES DRISCOLL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:, Page 1, line 56, for

"and" read an; line 90. for "finish" read furnish; page 2, line 46, for "W001" Patent should be read with these corrections therein that the same may conform to Signed and sealed this 29th day of September. A. D. 1931.

M. J. Moore, (Seal) Acting Commissioner of Patents.

the record of the case in the Patent Office. 

